Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare read-only, idempotent, non-destructive, closed-world, but the description goes well beyond them: it discloses that canceled records are included in the counts, the default window (7 days) and hard ceiling (31 days), the counting cap of 100, and UTC-day bucketing. Those are exactly the operational facts an agent cannot infer from the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, zero filler, and the trigger condition is front-loaded before the exclusion and the behavioral limits. Every clause (canceled inclusion, defaults, max range, cap, exclusions) carries distinct information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite an output schema existing, the description independently covers purpose, trigger, exclusions, result semantics, defaults, and limits. There is nothing an agent needs in order to call this correctly that is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description adds meaning the schema omits: the UTC day alignment that governs how startTime/endTime are bucketed, and the 31-day bound combined with a 100-count cutoff on results. This directly informs how an agent should choose the range.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (count), resource (scheduled records / appointment counts), and scope (one Veterical clinic, UTC day, bounded range, canceled included). The closing exclusion ('Not for seeing individual appointments, pets or owners') separates it from list_calendar_events and similar siblings without the agent needing to open their schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Opens with an explicit trigger ('Use this when the user wants to count scheduled records by UTC day') and adds a clear when-not clause ruling out per-appointment, pet, and owner lookups. It stops short of naming the alternative tool to use for those cases, so it is not quite a 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.